JP5337303B2 - Diagnostic method and apparatus for oil-filled electrical equipment - Google Patents

Description

  The present invention relates to an abnormality diagnosis for sulfide corrosion of a transformer, and more particularly to a technique for predicting the formation of copper sulfide on insulating paper.

  Sulfide corrosion is a phenomenon in which conductive copper sulfide is generated by a reaction between copper, which is a material of a transformer, and a sulfur component in insulating oil. Since this copper sulfide is a semiconductor, if it adheres to an insulator, insulation performance will fall. In particular, in large transformers and the like, since insulating paper is used for coil insulation, when copper sulfide adheres to the insulating paper, which is an insulator, a short circuit occurs between the coils, and the transformer is destroyed. However, the details of the generation mechanism were not known, and there was no effective diagnostic technique for existing transformers.

  Recently, the inventors conducted extensive research on the reaction mechanism involved in copper sulfide formation, and as a first step, a reaction occurs in which dibenzyl disulfide is adsorbed to the copper plate, and in the second step, dibenzyl disulfide reacts with copper. It was found that a reaction to form a dibenzyl disulfide-Cu complex occurs, and as a third step, a reaction in which the dibenzyl disulfide-Cu complex decomposes into a benzyl radical, a benzylsulfenyl radical, and copper sulfide occurs (non-patent document). Reference 1: S. Toyama, J. Tanimura, N. Yamada, E. Nagao, T. Amimoto, "Highly Sensitive Detection Method of Dibenzyl Disulfide and the Elucidation of the Mechanism of Copper Sulfide Generation in Insulating Oil", April 2009 , IEEE TDEI Vol16, No.2, pp509-515).

  If the technique of nonpatent literature 1 is used, insulating oil will be extract | collected from the existing transformer in operation, and the amount of copper sulfide produced | generated in the existing transformer can be estimated. Benzyl radical and benzylsulfenyl radical react with each other and with each other to produce bibenzyl, dibenzyl sulfide and dibenzyl disulfide as by-products. Information on the production of copper sulfide can be obtained by analysis of these by-products.

  However, even with the present technology, it could not be predicted whether or not the copper sulfide adheres to the insulating paper (Patent Document 1: JP 2010-10439 A).

  Except for the above technologies, there is no technology for predicting copper sulfide formation. Generally, dibenzyl disulfide, which is a causative substance of copper sulfide, is analyzed by oil analysis. The risk of copper sulfide formation by recovering the insulation oil inside and replacing it with new insulation oil, or processing the collected insulation oil to remove dibenzyl disulfide and then returning the treated insulation oil to the transformer (Patent Document 2: US Patent Application Publication No. 2008/0251424).

  There are many techniques for predicting transformer failures other than copper sulfide formation. There are also many methods for diagnosing abnormalities in overheating and discharge by detecting certain compounds. According to these methods, it is said that the soundness of a transformer can be diagnosed by analyzing a volatile component in oil generated due to deterioration of insulating paper or the like.

  For example, acetic acid, 3-pentanone, 2,5-dimethylfuran, butyraldehyde, 2-methoxyethanol, methanethiol, which is not detected from normal oil-filled electrical equipment during operation and is easily detected only when overheating or abnormal discharge occurs. Oil-filled electrical equipment characterized by diagnosing overheating abnormality or electric discharge abnormality inside the equipment from the presence or absence of detection of dimethyl sulfide, ammonia, 1,3-diazine, methylvinylacetylene, 2-methyl-1,3-butadiene An internal abnormality diagnosis method is known (Patent Document 3: Claim 2 of JP-A-9-72892, etc.).

  Abnormalities in oil-filled electrical equipment are often caused by insulation breakdown of coils, etc. due to copper sulfide adhering to the insulation paper. It is important to predict copper adhesion. However, even if the amount of copper sulfide generated in the oil-filled electrical device can be predicted by using the inventions of Non-Patent Document 1 and Patent Document 1, the generated copper sulfide adheres to the insulating paper. It cannot be judged whether or not there is. The invention of Patent Document 2 is also a technique related to copper sulfide generation in a transformer, but is not a technique capable of determining whether copper sulfide is generated on the surface of insulating paper. In addition, although the invention of patent document 3 is a technique which diagnoses abnormality of a transformer, the production | generation of copper sulfide cannot be judged.

JP 2010-10439 A US Patent Application Publication No. 2008/0251424 JP-A-9-72892

S. Toyama, J. Tanimura, N. Yamada, E. Nagao, T. Amimoto, "Highly Sensitive Detection Method of Dibenzyl Disulfide and the Elucidation of the Mechanism of Copper Sulfide Generation in Insulating Oil", April 2009, IEEE TDEI Vol16, No.2, pp509-515

  The present invention has been made to solve the above problems, and whether copper sulfide can be formed on the surface of insulating paper such as a coil immersed in insulating oil in an oil-filled electrical device. It is an object of the present invention to provide a method for diagnosing an oil-filled electrical device that can determine whether

The present invention is a diagnostic method for oil-filled electrical equipment for evaluating the risk of copper sulfide generation in oil-filled electrical equipment,
A first step of detecting a specific compound contained in the insulating oil in the oil-filled electrical device;
A second step for evaluating the possibility of copper sulfide generation in the oil-filled electrical device based on the detection result obtained in the first step;
A third step of diagnosing the risk of occurrence of abnormality in the oil-filled electrical device based on the evaluation result obtained in the second step,
The specific compound includes dibenzyl disulfide and / or a reaction product of a radical generated from dibenzyl disulfide,
Reaction products of radicals generated from di-tert-butyl-paracresol and / or di-tert-butyl-paracresol, or from di-tert-butyl-phenol and / or di-tert-butyl-phenol Including radical reaction products,
This is a diagnostic method for oil-filled electrical equipment.

  The specific compound preferably contains dibenzyl disulfide and di-tert-butyl-paracresol or di-tert-butyl-phenol.

  The reaction product of radicals generated from the dibenzyl disulfide is preferably at least one compound selected from the group consisting of benzaldehyde, benzyl alcohol, bibenzyl, dibenzyl sulfide and dibenzyl sulfoxide.

  The specific compound is a reaction product of a radical generated from dibenzyl disulfide and a radical generated from di-tert-butyl-paracresol, or a radical generated from dibenzyl disulfide and a di-tert-butyl-phenol. It is preferable that a reaction product with the radical to be included is included.

In the second step, when the specific compound is detected in the first step, it is evaluated that the possibility of copper sulfide generation in the oil-filled electrical device is high.
In the third step, when it is evaluated that the possibility of copper sulfide formation is high in the second step, it is preferable to diagnose that the risk of occurrence of abnormality in the oil-filled electrical device is high.

  The copper sulfide generation in the oil-filled electrical device is preferably copper sulfide generation on the surface of the insulating paper.

Further, the present invention is a diagnostic apparatus for oil-filled electrical equipment for evaluating the risk of copper sulfide generation in oil-filled electrical equipment,
A detection unit for detecting a specific compound contained in the insulating oil in the oil-filled electrical device;
Based on the detection result obtained by the detection unit, an evaluation unit for evaluating the possibility of copper sulfide generation in the oil-filled electrical device,
A diagnostic unit for diagnosing the risk of occurrence of abnormality in the oil-filled electrical device based on the evaluation result obtained by the evaluation unit;
The specific compound includes dibenzyl disulfide and / or a reaction product of a radical generated from dibenzyl disulfide,
Reaction products of radicals generated from di-tert-butyl-paracresol and / or di-tert-butyl-paracresol, or from di-tert-butyl-phenol and / or di-tert-butyl-phenol Including radical reaction products,
It also relates to diagnostic equipment for oil-filled electrical equipment.

  According to the diagnostic method of the present invention, not only dibenzyl disulfide but also di-tert-butyl-paracresol or di-tert-butyl in the analysis of insulating oil collected from existing oil-filled electrical equipment (transformers, etc.) -By detecting (measuring) phenol as well, it is possible to accurately evaluate the risk of copper sulfide generation on the surface of insulating paper such as coils immersed in insulating oil in oil-filled electrical equipment. Is played.

It is a graph which shows the correlation with the decreasing amount of DBDS, and the total amount of the reaction product of the radical produced | generated from DBDS. It is an example of the radical produced | generated from DBPC. It is another example of the radical produced | generated from DBPC. It is an example of the compound of the molecular weight 310 produced | generated by reaction of a benzyl radical and DBPC. It is a block diagram of the diagnostic apparatus of the oil-filled electrical apparatus of Embodiment 4. It is sectional drawing which shows the structural example of the oil-filled electrical equipment shown in FIG. It is the top view which showed one of the some winding layers which comprise a coil. It is sectional drawing which showed the cross section along the AA line of the winding layer shown in FIG. 10 is a graph showing test results of Test Example 3.

  As described above, as a mechanism for producing copper sulfide, as a first step, a reaction occurs in which dibenzyl disulfide (DBDS) is adsorbed on a copper plate, and as a second step, DBDS reacts with copper to form a DBDS-Cu complex. It has been found that the reaction takes place and, as a third step, a reaction occurs in which the DBDS-Cu complex decomposes into benzyl radicals and benzylsulfenyl radicals and copper sulfide.

  Of these compounds involved in the copper sulfide formation mechanism, only copper sulfide is insoluble in insulating oil. For this reason, if copper sulfide is generated on the copper plate surface, the copper sulfide cannot be transferred to the insulating paper.

  On the other hand, since the DBDS-Cu complex is a complex and exhibits oil solubility, the DBDS-Cu complex can be transferred from the copper plate surface to the insulating paper and adsorbed on the insulating paper surface. When the DBDS-Cu complex undergoes a reaction that decomposes into benzyl radicals and benzylsulfenyl radicals and copper sulfide on the surface of the insulating paper, copper sulfide is generated on the surface of the insulating paper.

  Furthermore, at the moment when the DBDS-Cu complex is radically decomposed on the surface of the copper plate, if other radicals are in the vicinity of the sulfur element, it is expected that the sulfur element and other radicals are radically bonded to return to the complex. Is done. As a result, the amount of copper sulfide generated on the copper plate surface is decreased and the amount of oil-soluble complex is increased, so that the amount of copper sulfide generated on the insulating paper surface is considered to increase. Therefore, when radicals other than radicals derived from DBDS coexist in the insulating oil, it is expected that the amount of copper sulfide produced on the insulating paper surface will increase.

  Such other radicals need to be stable and present in large amounts in the vicinity of elemental sulfur, such as di-tert-butyl-paracresol or di-tert-butyl-phenol (DBP). Radical antioxidants can be considered. The diagnostic method of the present invention is a reaction product of a radical generated from di-tert-butyl-paracresol and / or di-tert-butyl-paracresol (or di-tert-butyl-phenol and / or di-tert). -A reaction product of a radical generated from butyl-phenol) is detected. In the present invention, di-tert-butyl-paracresol is preferably 2,6-di-tert-butyl-paracresol (DBPC).

  DBDS, DBPC, and DBP can be detected by existing technology. For example, if a gas chromatograph / mass spectrometer is used, it can be quantified up to 0.1 ppmw.

(Embodiment 1)
An embodiment of a diagnostic method for oil-filled electrical equipment according to the present invention will be described. The diagnostic method of the present embodiment is a diagnostic method for an oil-filled electrical device that evaluates the risk of copper sulfide generation on the surface of insulating paper such as a coil in the oil-filled electrical device.
A first step of detecting a specific compound contained in the insulating oil in the oil-filled electrical device;
A second step for evaluating the possibility of copper sulfide generation in the oil-filled electrical device based on the detection result obtained in the first step;
And a third step of diagnosing the risk of occurrence of abnormality in the oil-filled electrical device based on the evaluation result obtained in the second step.

  Specifically, in the second step, when the specific compound is detected in the first step, it is evaluated that the possibility of copper sulfide generation in the oil-filled electrical device is high. Further, in the third step, when it is evaluated that the possibility of copper sulfide generation is high in the second step, it is diagnosed that the risk of occurrence of abnormality in the oil-filled electrical device is high.

  In the present embodiment, DBPC and DBDS are detected (measured) as specific compounds.

  In this embodiment, in the analysis of insulating oil collected from existing oil-filled electrical equipment (transformers, etc.), not only DBDS but also DBPC is detected (measured), so that it is immersed in the insulating oil in the oil-filled electrical equipment. It is possible to accurately evaluate the risk of copper sulfide generation on the surface of insulating paper such as a coil.

(Embodiment 2)
The present embodiment is a diagnostic method different from that of the first embodiment in that DBPC and a reaction product of radicals generated from DBDS are measured as the specific compound, and otherwise the same as in the first embodiment.

  DBDS and DBPC in the insulating oil are gradually consumed by using the insulating oil in the transformer. For this reason, even if the insulating oil contains DBPC and DBDS before use, DBDS and DBPC may not be detected when only DBDS and DBPC are measured after long-term use of the insulating oil. In such a case, there is a possibility that a place where a high risk should be diagnosed is mistakenly diagnosed as a low risk.

  In this embodiment, instead of measuring DBDS, it is possible to avoid such erroneous determination by detecting a compound (a reaction product of radicals generated from DBDS) that is generated when DBDS is consumed. it can.

  Examples of radical reaction products generated from DBDS include benzaldehyde, benzyl alcohol, bibenzyl, dibenzyl (mono) sulfide, and dibenzyl sulfoxide. These compounds can be analyzed using, for example, gas chromatography / mass spectrometry.

  FIG. 1 shows the reduction amount (consumption) of DBDS and the reaction products (benzaldehyde, benzyl alcohol, bibenzyl, dibenzyl (mono) sulfide and dibenzylsulfoxide) in sample oils A and B of Test Example 1 described later. The relationship with the total amount is shown. As shown in FIG. 1, there is a correlation between the total amount of these reaction products and the decrease in benzyl sulfide. For this reason, even if DBDS is not detected, it can be determined that DBDS has been added if these compounds are detected.

  Since these compounds have a correlation with the amount of DBDS decrease as an individual content, it is possible to prove that DBDS was present without using the total amount by measuring at least one of these compounds. .

  The detection of DBPC is based on whether the reaction product of DBPC and peroxy radical is analyzed using an appropriate analysis method, for example, a gas chromatograph mass spectrometer. I can judge. It is well known that DBPC easily becomes a radical as shown in FIG. 2A or 2B and reacts with radicals such as peroxy radicals.

(Embodiment 3)
This embodiment is different from Embodiments 1 and 2 in that a reaction product of a radical generated from DBPC and a radical generated from DBDS is measured as the specific compound. It is the same diagnostic method.

  Note that the reaction product of radicals generated from DBPC and radicals generated from DBDS is measured in the diagnostic method of the present invention by “the reaction product of radicals generated from dibenzyl disulfide and di-tert-butyl-para This corresponds to measurement of a “specific compound containing a reaction product of a radical generated from cresol”. That is, "detecting a specific compound containing a reaction product of a radical generated from dibenzyl disulfide and a reaction product of a radical generated from di-tert-butyl-paracresol" is a radical generated from dibenzyl disulfide. In addition to the case of detecting both of the reaction product of each other and the reaction product of the radicals generated from di-tert-butyl-paracresol, the radical generated from dibenzyl disulfide and di-tert-butyl-para The case where a reaction product with a radical generated from cresol is detected is also included.

  When DBPC and DBDS are added at the same time, a compound having a molecular weight of 310 is detected when the electrical insulating oil is analyzed with a gas chromatograph / mass spectrometer (GC / MS). The compound having a molecular weight of 310 is considered to be, for example, 4-benzyl-2,6-di-tert-butyl-4-methyl-2,5-cyclohexadienone (the structural formula is shown in FIG. 3). The compound is a reaction product of a radical generated from DBPC and a benzyl radical which is a radical generated from DBDS. Similar to the first embodiment in which DBPC and DBDS are detected only by detecting the compound, the risk of copper sulfide generation in the oil-filled electrical device can be evaluated.

  According to the diagnosis method of the present embodiment, even if DBDS and DBPC are consumed for the production of copper sulfide or the like due to the long-term use of insulating oil, the insulating paper in the oil-filled electrical device is applied as in the first embodiment. It can be judged that there is a high risk of copper sulfide adhering. Moreover, an oil-filled electrical device can be diagnosed simply by measuring only one type of compound.

  In the diagnostic method of the present invention, for example, DBDS and DBPC in insulating oil are detected, and 4-benzyl-2,6-di-tert-butyl-4-methyl-2,5-cyclohexadienone or the like is detected. The risk of copper sulfide generation in an oil-filled electrical device may be evaluated by detecting a reaction product of a radical generated from the DBDS and a radical generated from DBPC. In this case, since the concentration of DBDS and DBPC in the insulating oil before use can be estimated more accurately, the risk of copper sulfide generation on the surface of insulating paper in oil-filled electrical equipment should be more accurately evaluated. Can do.

  In Embodiments 1 to 3 described above, even when DBP is used as a detection target instead of DBPC, the risk of copper sulfide generation on the surface of insulating paper such as a coil immersed in insulating oil in an oil-filled electrical device Can be accurately evaluated.

(Embodiment 4)
The present embodiment is an embodiment of a diagnostic apparatus for realizing the method for diagnosing oil-filled electrical equipment in the above-described embodiment. In FIG. 4, the block diagram of the diagnostic apparatus of the oil-filled electrical equipment of this embodiment is shown. Referring to FIG. 4, diagnostic device 101 includes piping 2, tank 3, oil collecting device 4, pretreatment device 5, detection unit 6, evaluation unit 7, diagnostic unit 8, and display device 9. Is provided.

  FIG. 5 is a cross-sectional view illustrating a configuration example of the oil-filled electrical device illustrated in FIG. 4. Referring to FIG. 5, oil-filled electrical device 1 is, for example, a transformer, and includes a tank 50, iron cores 51 and 52, a coil 53, a cooler 54, and insulating oil 55.

  The iron cores 51 and 52 and the coil 53 are accommodated in the tank 50. The coil 53 is surrounded by the iron cores 51 and 52. The inside of the tank 50 is filled with insulating oil 55. Therefore, the coil 53 is immersed in the insulating oil 55.

  The insulating oil 55 is circulated in the oil-filled electrical device 1 by the pump 56. As indicated by the arrows in FIG. 5, the insulating oil 55 leaves the tank 50 and is cooled by the cooler 54. The cooled insulating oil 55 returns to the tank 50. The insulating oil 55 is, for example, mineral oil or synthetic oil.

  The coil 53 includes a plurality of winding layers stacked in one direction. FIG. 6 is a plan view showing one of a plurality of winding layers constituting the coil. 7 is a cross-sectional view showing a cross section taken along line AA of the winding layer shown in FIG.

  Referring to FIGS. 6 and 7, winding layer 53P is formed of paper-wrapped conductor 53L. The paper-wrapped conductor 53L is wound spirally in the same plane. The paper-wrapped conductor 53L includes a conductor 53M containing copper and an insulating paper 53N that covers the conductor 53M. The insulating paper 53N contains cellulose molecules.

  Returning to FIG. 4, the tank 3 is connected to the oil-filled electrical device 1 by the pipe 2. When the insulating oil 55 is collected from the oil-filled electrical device 1, part of the insulating oil in the oil-filled electrical device 1 flows into the tank 3 through the pipe 2. The oil collecting device 4 is a pump, for example, and collects the insulating oil in the tank 3. The insulating oil in the tank 3 is used for detection of a specific compound by the detection unit 6. The pretreatment device 5 performs pretreatment of the insulating oil before the insulating oil in the tank 3 is sent to the detection unit 6. In the detection unit 6, the residual concentration of the specific compound is measured.

  The evaluation unit 7 and the diagnostic unit 8 are configured by a computer, for example, and execute arithmetic processing based on a map and a program stored therein. Specifically, the evaluation unit 7 receives the measurement value of the specific compound from the detection unit 6 and evaluates the possibility of copper sulfide generation in the oil-filled electrical device. The diagnosis unit 8 receives the evaluation result of the evaluation unit 7 and diagnoses the risk of occurrence of abnormality in the oil-filled electrical device electricity.

  The display device 9 displays the diagnosis result of the diagnosis unit 8, that is, the risk of occurrence of abnormality of the oil-filled electrical device on a screen (not shown). Thereby, it becomes possible to grasp the diagnosis result by the diagnosis apparatus 101.

  Hereinafter, regarding the diagnostic method of the present invention, the amount of dibenzyl disulfide contained in the insulating oil and the compound derived from di-tert-butyl-paracresol or di-tert-butyl-phenol, and the surface of the insulating paper The result of the test which confirmed the relationship with the production | generation of copper sulfide is shown.

(Test Example 1)
First, a naphthenic transformer oil (sample oil A) that has been confirmed to contain no corrosive sulfur by ASTM D 1275B is prepared. Next, a predetermined amount of dibenzyl disulfide is added to the transformer oil. In this experiment, 100 ppmw (w / w) was added. This oil is designated as sample oil B. An oil obtained by adding 0.4 wt% (w / w) of DBPC to sample oil B is referred to as sample oil C.

  Using these insulating oils, a test relating to the formation of copper sulfide is performed by a method in accordance with IEC 62535 of the IEC (International Electrotechnical Commission) standard. 15 grams of this transformer oil and a copper plate (30 mm x 7.5 mm x 1.5 mm) wrapped with one layer of kraft paper are sealed in a bottle with an internal volume of 30 cc, and a silicone rubber stopper is applied, and then at a temperature of 150 to 24 ° C. Heat for 144 hours.

Table 1 shows the relationship between the state of copper sulfide adhesion on the surface of the insulating paper after the test and the heating time. The numerical values in the table are used as follows.
1: No copper sulfide adhered 2: Slightly adhered to the edge of the insulating paper 3: Adhered more extensively than 2: 4: Adhered to the entire surface

As shown in Table 1, in sample oil A, since dibenzyl disulfide which is a raw material for copper sulfide is not added, copper sulfide is not generated. In the sample oil B, the production of copper sulfide on the insulating paper surface is observed. As a result of analyzing the amount of copper sulfide deposited, it was 1.9 (1st day) to 9.5 μg / cm ² (6th day). In sample oil C, significant formation of copper sulfide is observed on the surface of the insulating paper. As a result of analysis of the amount of copper sulfide deposited, it was 48 (1st day) to 47.7 μg / cm ² (6th day).

  For this reason, when the sample oil C is used, it can be said that the risk is about five times higher than that when the sample oil B is used. That is, it can be determined that a transformer using insulating oil to which DBDS and DBPC are added is high risk (the risk of occurrence of abnormality is high).

(Test Example 2)
The following examination was performed by the same method as Test Example 1 except that paraffinic mineral oil was used instead of naphthenic mineral oil.

  Prepare a paraffinic transformer oil (sample oil D) that has been confirmed to be free of corrosive sulfur by ASTM D 1275B. Next, oil obtained by adding 100 ppmw of dibenzyl disulfide to this transformer oil (sample oil D) is referred to as sample oil E. The oil obtained by adding 0.4% by weight of DBPC to the sample oil E is referred to as sample oil F.

  Using these insulating oils, a test relating to the formation of copper sulfide was performed by a method based on IEC62535. 15 grams of this transformer oil and a copper plate (30 mm x 7.5 mm x 1.5 mm) wrapped with one layer of kraft paper are sealed in a bottle with an internal volume of 30 cc, and a silicone rubber stopper is applied, and then at a temperature of 150 to 24 ° C. Heat for 144 hours.

  Table 2 shows the relationship between the copper sulfide adhesion on the surface of the insulating paper after the test and the heating time. The numerical values in the table are used in the same meaning as in Table 1.

As shown in Table 2, in sample oil D, copper sulfide is not generated because dibenzyl disulfide that is a raw material for copper sulfide is not added. In the sample oil E, copper sulfide is generated on the surface of the insulating paper. As a result of analyzing the adhesion amount of copper sulfide, the adhesion amount was 3.5 μg / cm ² (1st day) to 10.7 μg / cm ² (6th day). In the sample oil F, significant formation of copper sulfide is observed on the surface of the insulating paper. As a result of analyzing the adhesion amount of copper sulfide, the adhesion amount was 4.8 μg / cm ² (1st day) to 53.1 μg / cm ² (6th day).

  For this reason, when the sample oil F is used, it can be said that the risk is about five times as high as the case where the sample oil D is used. That is, it can be judged that a transformer using insulating oil to which DBDS and DBPC are added is high risk.

(Test Example 3)
In Test Examples 1 and 2, the experiment was performed with the DBPC concentration fixed at 0.4% by weight. In this test example, in order to clarify the influence of the concentration of DBPC on the amount of copper sulfide on the surface of insulating paper, the concentration of DBPC was set to 0, 0.02, 0.04, 0.1, 0.2, The test regarding the production | generation of copper sulfide similar to the test example 1 was done by setting 0.4 and 0.8 and the density | concentration of DBDS as 100 ppmw, and the copper sulfide adhesion amount on the insulating paper was measured. FIG. 8 shows a graph in which the copper sulfide adhesion amount on the insulating paper is plotted against the concentration of DBPC.

  As shown in FIG. 8, even when the concentration of DBPC is 0.02% by weight, the amount of copper sulfide deposited on the insulating paper is clearly increased as compared with the case of no addition. In addition, up to 0.2 wt% DBPC addition, the amount of copper sulfide on the surface of the insulating paper increases as the DBPC concentration increases, and after reaching 0.2 wt% as the maximum value, the DBPC concentration increases thereafter. As a result, the amount of copper sulfide on the insulating paper decreased.

(Test Example 4)
In Test Examples 1 to 3, experiments were conducted using DBPC as an antioxidant. In this test example, an experiment using DBP (di-tert-butyl-phenol) as an antioxidant was performed. That is, the same naphthenic transformer oil (sample oil A) as in Test Example 1 and the oil obtained by adding 0.4 wt% DBP and 100 ppmw DBDS to Sample Oil A (Sample Oil G) The same experiment was conducted.

  Table 3 shows the relationship between the state of copper sulfide adhesion on the surface of the insulating paper after the test and the heating time. The numerical values in the table are used in the same meaning as in Table 1.

  As shown in Table 3, in the case of DBP, the amount of copper sulfide adhering to the surface of the insulating paper was small compared to the case of DBPC, and the entire surface did not adhere, but when no antioxidant was added (Table Compared with the sample oil B) of No. 1, the amount of copper sulfide deposited on the surface of the insulating paper was clearly increased. Therefore, it can be judged that the transformer using the insulating oil to which DBP is added together with DBDS has a higher risk than the transformer using the insulating oil to which DBP or DBPC is not added.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Oil-filled electrical equipment, 2 piping, 3,50 tank, 6 detection unit, 7 evaluation unit, 8 diagnostic unit, 9 display device, 51,52 iron core, 53 coil, 53L paper winding conductor, 53M conductor, 53N insulating paper, 53P Winding layer, 54 cooler, 55 insulating oil, 56 pump, 101 diagnostic device.

Claims (7)

A method for diagnosing oil-filled electrical equipment (1) for evaluating the risk of copper sulfide generation in the oil-filled electrical equipment (1),
A first step of detecting a specific compound contained in the insulating oil (55) in the oil-filled electrical device (1);
A second step of evaluating the possibility of copper sulfide generation in the oil-filled electrical device (1) based on the detection result obtained in the first step;
A third step of diagnosing the risk of occurrence of abnormality in the oil-filled electrical device (1) based on the evaluation result obtained in the second step,
The specific compound includes dibenzyl disulfide and / or a reaction product of a radical generated from dibenzyl disulfide,
Reaction products of radicals generated from di-tert-butyl-paracresol and / or di-tert-butyl-paracresol, or from di-tert-butyl-phenol and / or di-tert-butyl-phenol Including radical reaction products,
Diagnosis method for oil-filled electrical equipment (1).   The diagnostic method for oil-filled electrical equipment (1) according to claim 1, wherein the specific compound includes dibenzyl disulfide and di-tert-butyl-paracresol or di-tert-butyl-phenol.   The diagnosis product according to claim 1, wherein the reaction product of the radical generated from the dibenzyl disulfide is at least one compound selected from the group consisting of benzaldehyde, benzyl alcohol, bibenzyl, dibenzyl sulfide and dibenzyl sulfoxide. Method.   The specific compound is a reaction product of a radical generated from dibenzyl disulfide and a radical generated from di-tert-butyl-paracresol, or a radical generated from dibenzyl disulfide and a di-tert-butyl-phenol. The diagnostic method of Claim 1 containing the reaction product with the radical which carries out. In the second step, when the specific compound is detected in the first step, evaluate that the possibility of copper sulfide generation in the oil-filled electrical device (1) is high,
In the third step, when it is evaluated that the possibility of copper sulfide generation is high in the second step, it is diagnosed that the risk of occurrence of abnormality in the oil-filled electrical device (1) is high. The diagnostic method of the oil-filled electrical apparatus (1) described.   The diagnosis method of the oil-filled electrical device (1) according to claim 1, wherein the copper sulfide generation in the oil-filled electrical device (1) is copper sulfide generation on the surface of the insulating paper (53N). A diagnostic device (101) for an oil-filled electrical device (1) for evaluating the risk of copper sulfide generation in the oil-filled electrical device (1),
A detection unit (6) for detecting a specific compound contained in the insulating oil (55) in the oil-filled electrical device (1);
An evaluation unit (7) for evaluating the possibility of copper sulfide generation in the oil-filled electrical device (1) based on the detection result obtained by the detection unit (6);
A diagnostic unit (8) for diagnosing the risk of occurrence of abnormality in the oil-filled electrical device (1) based on the evaluation result obtained by the evaluation unit (7),
The specific compound includes dibenzyl disulfide and / or a reaction product of a radical generated from dibenzyl disulfide,
Reaction products of radicals generated from di-tert-butyl-paracresol and / or di-tert-butyl-paracresol, or from di-tert-butyl-phenol and / or di-tert-butyl-phenol Including radical reaction products,
Diagnostic device (101) for oil-filled electrical equipment (1).

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